The Mysterious Syndrome X

By David Mendosa

In his Banting Lecture at the American Diabetes Association's 1988 annual meeting Dr. Gerald Reaven first described how insulin resistance leads to what he called Syndrome X. It was a brilliant analysis.

‘The common feature…is insulin resistance.’

But the name Syndrome X was an unfortunate choice of terminology. The first problem was that medicine already had a quite different Syndrome X. Coined by H.G. Kemp in 1973, it describes the genuine mystery of why some patients have chest pains but normal coronary arteriograms.

Second, the letter X represents the unknown, whether it referred to hidden conspiracies on Fox Television's X-Files or the unknown variable in algebra. When Reaven used the term Syndrome X he was describing a mystery and an unknown cause of heart disease. But it is now well known and all too common.

The topic is so hot in fact that in the past two years at least four books about Syndrome X have appeared. Only one of these, however, is worth reading. Reaven's, Syndrome X: Overcoming the Silent Killer That Can Give You a Heart Attack, is his first book for a lay audience. He has written more than 500 professional papers and books.

"I wrote this lay book because I was getting disgusted with all the diet books that started with my work and twisted it in ways that were totally wrong," he told me. His Syndrome X Diet is 45 percent carbohydrate, 15 percent protein, 30-35 percent polyunsaturated and monounsaturated fats, and 5-10 percent saturated fats.

Nowadays, Syndrome X is sometimes better known as the insulin resistance syndrome. "The common feature of the proposed syndrome is insulin resistance," Reaven said originally, " and all other changes are likely to be secondary to this basic abnormality. The fact that all of them may not necessarily be seen in the same individual should not minimize their importance."

Originally, Reaven named five other changes or components of Syndrome X in addition to insulin resistance itself. They are levels of glucose, insulin, blood triglycerides, and blood pressure that are above normal, and HDL (good) cholesterol that is too low. Subsequently, he's added more components to the syndrome, including smaller, denser LDL cholesterol particles, slow clearing of blood fats after meals, and poor ability to break up blood clots.

Insulin resistance is associated with each of these components, all of which increase the risk of coronary artery disease. Syndrome X "may be responsible for as many as 50 percent of all heart attacks—or even more," Reaven writes in his book.

About 25 to 30 percent of all Americans have this syndrome, according to his research. That could make insulin resistance the most common cause of chronic disease, says epidemiologist Rodolfo Valdez of the U.S. Centers for Disease Control and Prevention.

Not everyone who is insulin resistant develops diabetes. The beta cells in our pancreases are usually able to pump out enough insulin to compensate for our body's resistance to it. It's only when the beta cells can't keep up that we develop type 2 diabetes.

But what causes insulin resistance in the first place? And besides the Syndrome X Diet what can we do about it? The answers to those questions will appear in a subsequent article.

This article originally appeared on HealthTalk Interactive, but is no longer online there.